Will these lights fit on Trex deck posts I previously bought caps that were supposed to be universal but will not fit my Trex posts

These lights fit on my post covers. The base of the light has several removable adapters that allow it to fit over several different sized posts. If you bought caps that fit over bare posts (3.5x 3.5 inches) then they won't fit over the 4x4 trex post covers.

This post cap will fit on a post that measures 3.5-in x 3.5-in, 4-in x 4-in, 4-1/4-in x 4-1/4-in and 4-1/2-in x 4-1/2-in. It will not fit on any other sized post.